ACL2 is a mathematical logic, programming
language, and mechanical theorem prover based on
the applicative subset of Common Lisp. It is an
"industrial-strength" version of the NQTHM or
Boyer/Moore theorem prover, and has been used for
the formal verification of commercial
microprocessors, the Java Virtual Machine,
interesting algorithms, and so forth.

APEye is a jQuery widget for issuing HTTP requests, designed to help document and test APIs. With a few lines of Javascript, you can let users experiment with your API without leaving the documentation. Unlike hurl and apigee, requests are handled entirely by the client; no server-side proxy is needed.

AWbot is a bot that connects to your Web site and makes URL requests
like human visitor. It's not a Web indexing robot, but a Web client
tool that emulates visitors browsing your Web site to test its
stability after a development change, its reliability, and its
response to heavy loads.

Abbot is a framework for testing Java GUIs. It lets you launch an application or GUI component, play back user actions on it, and examine its state. Tests may be coded or scripted. The editor supports recording user actions into a script, exploring the component hierarchy, running the script, and other features you'd expect from a script editor. Test scripts are JUnit extensions.

Accerciser lets you test all aspects of
accessibility on the GNOME desktop. It uses AT-SPI
to inspect and control widgets, allowing you to
check whether an application is providing correct
information to assistive technologies and
automated test frameworks. It has a simple plugin
framework that you can use to extend and customize
the accessibility information displayed. It is
written in Python and uses the pyLinAcc component
from LSR to interact with AT-SPI using pyORBit. In
essence, it is a next generation at-poke tool.

AceUnit (Advanced C and Embedded Unit) is a
comfortable C code unit test framework. AceUnit is
in the style of JUnit 4.x, and is easy, modular,
and flexible. AceUnit can be used in resource
constraint environments such as embedded software
development.

Achoo is a fluent interface for unit testing
Python objects. Achoo makes it easy to make
assertions about the properties and behaviors of
Python objects. For example, is this object equal
to this other one? Does calling this function with
these arguments raise an error?

AePro is a compilation manager for programs
written in progres4gl. It compares modification
times and will only (re)compile the programs whose
source code has changed. It is intended to be used
in combination with Aegis, a transaction-based
software configuration management system that
provides a framework within which a team of
developers may work on many changes to a program
independently.

Aegis is a transaction-based software configuration management system. It provides a framework within which a team of developers may work on many changes to a program independently, and Aegis coordinates integrating these changes back into the master source of the program, with as little disruption as possible. Aegis supports geographically distributed development.